EVALUATION OF ASPHALTENE PRECIPITATION IN DIFFERENT CONDITIONS OF COMPOSITION, TEMPERATURE, AND PRESSION

Asphaltenes are a heavy fraction of petroleum with the ability for self-association, a phenomenon that can occur spontaneously in the reservoirs or in any of the various stages of production and processing, depending on variations in pressure, temperature, composition and shearing, among others. In this work, it was evaluated the precipitation of asphaltenes in two oils (P01 and P02) in different conditions of temperature and pressure and in the absence or presence of CO2. Under high pressure and temperature conditions, the precipitation of asphaltenes was observed in the presence of CO2 in mixtures with methane, while the addition of propane induced precipitation in the absence of CO2. The results of analyses elemental (CHNO), SEM, FTIR and LDI-MS were consistent with the structure assigned to samples of this nature (oils, maltenes and fractions of asphaltenes insoluble in n-pentane, C5I, and n-heptane, C7I).沥青质(Asphaltenes)是石油的重质组分，具备自缔合能力。该现象可在油藏中自发发生，亦可在生产与加工的各阶段出现，其发生取决于压力、温度、组分组成及剪切作用等多种因素的变化。本研究针对两种原油（P01与P02），在不同温压条件及有无二氧化碳(CO₂)存在的工况下，评估了沥青质的析出情况。在高温高压条件下，当体系中存在二氧化碳并与甲烷混合时，可观测到沥青质析出；而在未添加二氧化碳的工况下，丙烷的加入会诱发沥青质析出。本研究采用元素分析（CHNO）、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)以及激光解吸电离质谱(LDI-MS)对样品进行表征，所得结果与该类样品（原油、脱沥青质组分(maltenes)以及正戊烷不溶沥青质组分(C5I)、正庚烷不溶沥青质组分(C7I)）的推定结构相一致。